Removing PCT Valve and Cleaning [1997 Volvo GLT Turbo]

Post by **1997volvo850** » 18 Apr 2010, 17:04

I played around with my PCV system today.

I hooked a vacuum to the exhaust hose that goes from the oil separator to the PCT valve.

I was able to feel the vacuum at the oil dipstick tube and at the vent on top of the engine.
I believe there are no obstructions in my PCV system but I am not able to check the vent
under the intake manifold to the right of the oil separator.

I tried attaching a balloon to the oil dipstick tube. Some exhaust went into the balloon but
there was NOT enough pressure to make the balloon rise. I believe this means that my recently
cleaned PCT valve is helping to reduce pressure buildup in the engine.

Correct me if I'm wrong, but the balloon should stand up if there is significant pressure, right?

I did increase the size of the PCT valve exhaust hole by about 1/16". I did not see a reduction
in exhaust from the oil dipstick.

I will try to increase the hole a little more the next time I have it out. I suspect the gases are to voluminous
for the PCV system to eliminate. This may be because of more blow by or bad rings.

I think I'm going to hold off on installing the PCV kit right now. I need to determine where the white
smoke in my exhaust is coming from. I did check my plugs and my plugs and pistons were covered
in carbon. I may try to Seafoam my engine next.

TIKIFULWOOD · Post by **TIKIFULWOOD** » 28 May 2010, 12:10

Having just checked this thread, I went outside and cleaned the pct valve. Not that I have any major, noticable smoke coming from my dipstick, but just to do one of those jobs etc.

Results thus; No blockage at all. Yes there was minimal crustation on the walls of the valve resulting in blockage of the vacuum pipe outlet (small horizontal) but the verticle section was really good. The rubber mounting was serviceable with no perishing, and the only discovery was the vacuum elbow had perished. They're everywhere those little critters, so I'm happy i've found another one to replace. I've called him 'graham'.!

Maybe the cars of you guys over the pond react significantly differently to ours in the uk/europe due to climate etc, or whether it's just down to I don't use mine for going to the shops much. Anyway, be good to hear of any uk cars with the same issue's as yours. But, I'm yet to look into the PCV condition...

I'll probably find half of the BP shareholders encrusted to it.

Post by **cn90** » 05 Dec 2012, 08:58

I have my turbo hose out of the car and cleaned the PTC.
I will re-use the hose/PTC for now until I get an OBD code (i.e. no need for new hose yet).

Does anyone have a diagram of PTC operation, I just curious how it works (theory of operation).

Post by **jblackburn** » 05 Dec 2012, 09:02

Pretty simple really:

-Small vacuum hose provides oil suction at idle directly to the intake manifold, much like a traditional PCV system on most other cars that just vent it directly to the intake manifold.

-Large hose goes to the oil separator, which pulls a vacuum at higher RPMS and sucks the oil out of the compressor wheel side of the turbo that blows past the turbo seals, dumps it back into the oil separator box, which goes back into the oil pan. This keeps much of the oil from depositing on the intake valves.

Post by **1997volvo850** » 02 Jun 2016, 19:29

After starting this thread a few years ago I'm just a tad embarrassed to report I let things get to the point of blockage.

: My baby's sending me a message...

I asked my baby if she's been under a lot of pressure lately and she answered in no uncertain terms.

: Glove inflates slightly with dipstick pulled out.

And when I put it all the way in.

: Lots of pressure

Last time I worked on the PTC I found cleaning the opening solved my problem and allowed fumes to once again exit into the intake. I believe this procedure also addresses pressure buildup in the engine. My PCT was blocked and the main source of my woes at that time. I avoided replacing the PCV system at that time.

I'll report back as I investigate this issue further. I'll discuss the oil leak in a separate thread.

Post by **jreed** » 03 Jun 2016, 04:18

Thanks for following up and for sharing this photo sequence. A classic!

Post by **abscate** » 03 Jun 2016, 05:25

Remember that PTC is not a valve, it's just a hole that needs to be open. The electrical connection is just a resistive heater that helps keep the oil vapour as a gas.

The real problem is when the crud is so bad it blocks the engine block ports. That's much harder to clean.

Post by **1997volvo850** » 03 Jun 2016, 10:26

abscate: I'm planning to overhaul my PCV system. My problem is I bought the FCP kit with Uro hoses so I've been terrified to install it. I will likely buy OEM hoses. I'm wondering if cleaning the current box is better than installing the one from FCP.

I was very surprised at how clogged my PTC was. I would not be surprised if the engine blocks port is plugged too but there is significant venting via the dipstick tube - which tells me fumes are getting into oil drain and pushed out dipstick tube. I'm assuming the cam vent and block vent are independent.

The only question is whether the block vent is completely blocked. I will inspect the opening on the top of the engine. Difficult to inspect the one
into the block that's under the IM.

This is what you get when you ask the Volvo Service Department to design a breather system that folks will talk about for a long time. :^(

Post by **jblackburn** » 04 Jun 2016, 17:50

Box is probably fine, but I would advise against using the URO hoses - you'll have to do it all again in a year.

Hopefully no serious buildup in the oil pan ports.

Post by **1997volvo850** » 04 Jun 2016, 20:25

I checked the PTC valve and it was blocked solid. The tiny vacuum line to the intake manifold was blocked solid and broken off. Where it broke off was completely solid with gunk. The large hose to breather box broke off just inside the thick insulation near the PTC valve. It was not blocked. Only the PTC was blocked solid.

One question I have is why are materials that don't hold up to heat/oil used for the critical PCV system. I believe the Volvo OEM parts eventually get brittle and fall apart too. Metal lines seem like they would last forever and you could simply clean them every 60K miles.

I'm coming to the conclusion that a clogged (under appreciated) PTC valve has the potential for causing a massive amount of damage to our vehicles. If the rest of the breather system is fine a clogged PTC can blow out any number of seals causing serious amounts of repairs costs.

To think a clogged opening the size of a pencil eraser can result in blowing out the rear main seal is impressive!!

I'll stick to PTC issues here and plan to research this a bunch more before I write some differing opinions of the PCV and PTC recommendations on this site.

Update: I stopped by Dave's in Ithaca and he replaced the rear cam exhaust seal. I lucked out big time on this one.

Removing PCT Valve and Cleaning [1997 Volvo GLT Turbo]

Re: Removing PCT Valve and Cleaning [1997 Volvo GLT Turbo]